1. Field of the Invention
The present invention provides nucleotide sequences coding for ptsH and processes for the fermentative preparation of L-amino acids, particularly L-lysine, in which the ptsH gene is enhanced, using coryneform bacteria.
2. Background Information
L-amino acids, particularly L-lysine, are used in human medicine and in the pharmaceutical industry, and particularly in animal nutrition.
It is known to prepare L-amino acids by fermentation of strains of coryneform bacteria, particularly Corynebacterium glutamicum. In view of the great importance, work is constantly being carried out to improve the preparation processes. Process improvements may relate to measures involving the fermentation technique, such as, e.g., agitation and oxygen supply, or the composition of the nutrient media such as, e.g., the sugar concentration during fermentation, or the work up to the product form by, e.g., ion exchange chromatography, or the intrinsic performance properties of the microorganism itself.
In order to improve the performance properties of said microorganisms, methods of mutagenesis, selection and mutant selection are employed. Strains thereby obtained are resistant to antimetabolites such as, e.g., the lysine analogue S-(2-aminoethyl) cysteine, or auxotrophic for metabolites of regulatory importance and produce L-lysine.
For some years, methods of recombinant DNA technology have also been used to improve strains of coryneform bacteria producing L-amino acids by amplifying individual biosynthesis genes for L-amino acids and examining the effect on L-amino acid production. Review articles on this subject may be found inter alia in Kinoshita (“Glutamic Acid Bacteria”, in: Biology of Industrial Microorganisms, Demain and Solomon (Eds.), Benjamin Cummings, London, UK, 1985, 115–142), Hilliger (BioTec 2, 40–44 (1991)), Eggeling (Amino Acids 6:261–272 (1994)), Jetten and Sinskey (Critical Reviews in Biotechnology 15, 73–103 (1995)) and Sahm et al. (Annuals of the New York Academy of Science 782, 25–39 (1996)).